Hi Papcina,
Wow! This thread stirred some dormant memory cells.

Back in 1998/99 I did al lot of Award BIOS patching for these 486 boards.
Your 09/26/94-SIS-85C471B/E/G-2C4I9S23-00 Rev.G2. is indeed the latest BIOS from Soyo for the 25J/K/L.
However, I have a newer 11/28/95-SIS-85C471B/E/G- BIOS, specially adapted for the 25J/K/L. This BIOS adds full AMD Am5x86-133 support incl. L1 cache Write-Back mode, and fixes the 2GB HDD display limit bug for correct support of drives up to 8GB. In addition this BIOS is Y2000 compliant.
If you don't have any plans to update your CPU or HDD, you can stick to the Rev.G2. BIOS but if you do, I can send you this updated BIOS.
Unfortunately, this new BIOS has no boot from CD-ROM either. I've never seen that in 486 and early Pentium BIOSes. This feature came years later and adding that to an old BIOS goes way above my expertise...
For detailed info on running the Am5x86-133 on a socket2/3 board, see my article at
http://web.inter.nl.net/hcc/J.Steunebrink/amd5x86.htm You will also find my PM address there.
Greetings, Jan.